Device for separation and collection of plasma

Abstract

A method for separating and collecting cell-free plasma by finger stick that minimizes contamination with genomic DNA from a donor. The method comprising placing a tourniquet on one of the digits of the donor's finger to apply pressure, lancing the digit to create an incision in the digit, and collecting blood from the incision from the incision site. The collected blood is placed on a separation membrane wherein the separation membrane is in contact with a collection membrane and both the separation and collection membrane are inserted into a substrate configured to provide overlap between the membranes. A kit and instructions for carrying out the method is also provided.

The invention claimed is: 
     
       1. A method of separating and collecting a cell-free plasma sample that minimizes contamination with genomic DNA (Deoxyribonucleic Acid) from a donor, the method comprising:
 placing a tourniquet on a digit of the donor's hand to apply pressure; 
 lancing the digit to create an incision in the digit; 
 collecting blood from the incision; 
 dispersing the collected blood onto a separation membrane wherein the separation membrane is in contact with a collection membrane and said separation and collection membranes only overlap at a portion of the collection membrane defined as an overlapping contact area for both said membranes, wherein both the separation membrane and the collection membrane are inserted into a substrate configured to provide overlap between said membranes at the defined overlapping contact area; and 
 collecting the cell-free plasma sample on the defined overlapping contact area, 
 wherein the collected cell-free plasma sample contains cell-free DNA and is substantially free of genomic DNA, and 
 wherein the substrate further comprises: 
 an inner flexure defined by a plurality of first slots in the substrate, disposed proximate to a first peripheral portion of the substrate; 
 an outer flexure defined by a plurality of second slots in the substrate, disposed surrounding at least a portion of the plurality of first slots; 
 wherein the inner flexure comprises a first distal end portion and the outer flexure comprises a second distal end portion overlapping with a fraction of the first distal end portion of the inner flexure, and 
 means for holding and aligning the separation membrane to position along the inner flexure, said means located between the first peripheral portion and a first proximal end portion of the inner flexure. 
 
     
     
       2. The method of  claim 1 , wherein an overlapping contact distance of the overlapping contact area in the longitudinal direction is in a range from about 1 mm to about 2 mm. 
     
     
       3. The method of  claim 1 , further comprising: positioning the separation membrane and the collection membrane on the substrate and forming the overlapping contact area between the separation membrane and the collection membrane. 
     
     
       4. The method of  claim 3 , wherein forming the overlapping contact area further comprises forming the overlapping contact area between a distal end of the separation membrane and a proximal end of the collection membrane. 
     
     
       5. The method of  claim 3 , further comprising: applying a pressure at the overlapping contact area. 
     
     
       6. The method of  claim 3 , wherein the overlapping contact area is in a range of about 8 mm 2  to about 16 mm 2 . 
     
     
       7. The method of  claim 1 , further comprising: separating the collected blood using the separation membrane and collecting the plasma sample using the collection membrane, wherein both separating and collecting are by a capillary flow. 
     
     
       8. The method of  claim 1 , where the tourniquet is an elastic material or a rubber band. 
     
     
       9. The method of  claim 1 , further comprising removing a first blood immediately after lancing while still applying pressure. 
     
     
       10. The method of  claim 1 , wherein the collecting step further comprises holding a capillary tube against the blood formed from the incision to collect the blood. 
     
     
       11. The method of  claim 1 , wherein the collecting step is carried out without milking the finger. 
     
     
       12. The method of  claim 1 ,
 wherein the dispersing step further comprises applying pressure by an external force on the separation membrane and the collection membrane about the defined overlapping contact area.